1. Field of the Invention
The present invention concerns a method and a device for moving a free-swinging load from a starting point to a destination.
2. Description of the Prior Art
A robot can transport a load that is free-swinging relative to a suspension point of the robot, for example in the field of material handling or in the field of logistics. The load can be set into oscillations, for example due to accelerations during the transport, such that this in particular is still swinging when the robot or the suspension point has reached its destination. A targeted depositing of the load immediately after reaching the destination is thereby at least hindered or entirely impossible. The robot can wait until the load has a sufficiently low oscillation in order to enable a targeted depositing.
In order to attenuate oscillations of the load during the transport, DE 42 38 795 A1 discloses to arrange a rotation axis sensor or acceleration sensor near a pendulous load to measure the angular velocity or the angle of inclination of the load relative to a coordinate system fixed relative to the surface of the earth. Due to the measured, current angular velocity of the load, its suspension point or the length of a cable with which the load is suspended freely swinging at the suspension point is varied to damp the oscillation. A relatively complicated regulation with a feedback loop for the suspension point is thus realized based on the measured values of the rotation axis sensor or acceleration sensor, the performance of which regulation in particular depends on the quality of the sensor signals.
DE 102 23 670 A1 discloses a method for operating a robot that comprises a gripping tool connected with a hand of the robot. The robot can lift an object with the gripping tool and transport it from a starting point to a destination. In order to avoid the object tearing away from the gripping tool caused by accelerations during the transport of the object, during the transport of the object the robot rotates its hand such that essentially only normal forces act between the object and the gripping tool. However, the object is not freely suspended during the transport but rather is firmly connected with the hand via the gripping tool so that, via the rotation of the hand, the object is brought into the position established according to the rotation during its transport.